SU1659785A1 - Method for determining grain-size analysis of concrete aggregates - Google Patents

Abstract

The invention relates to measuring equipment, namely, a method for determining the fractional (particle size) composition of bulk materials, and is intended for use in the construction industry, as well as in other areas of national economy where it is necessary to control the grain size distribution of bulk materials, for example, in coke-chemical and metallurgical. The aim of the invention is to ensure continuous monitoring of the composition of the aggregates of concrete and to reduce the time for its holding. To improve the performance and ensure control of the composition of the aggregates, the particle size distribution is determined during sieving of the material on sieves with standard cell sizes, and the fractions weights are determined by signals from a load cell on the bottom of the vibroorgan during the joint movement of the layer of material with the vibroorgan. The measurement is carried out during the period of joint motion of the material layer with moving gratings during one oscillation period in the range of variation of the phase angle of oscillations of 9/6 lp-11/6 7G + 2tgp, where n is the vibration number of the vibroorgan. 1 ill., 1 tab. (L

Description

The invention relates to a measurement technique, in particular, to a method for determining the content in grains of grains of the required fractions, and can be used in the construction industry and in a number of other branches of the national economy where it is required to control the granulometric composition of polydisperse granular materials, for example, in mining, chemical industry, etc,

The purpose of the invention is to ensure continuous monitoring of the composition of concrete aggregates and to reduce the time for its holding.

The drawing shows a diagram of the device with which the proposed method can be implemented.

The device consists of a frame 1, on which vibroorgans 2-5 are installed on elastic supports (in the case of determining the fractional composition of building rubble, the lattice bottoms of vibroorgans have holes of 20, 15 and 10 mm, respectively, the bottom of the lower vibroorgan are solid), loading device (bunker) 6 7, 8, and a mass measuring system, including force sensors 9-12 (contact-dynamic

ate

""but

pressure sensors), recording 13 and summarizing 14 devices.

Example. Determine the granulometric composition of crushed stone fractions 5-10 and 10-20 mm,

The test material was fed into the hopper 6, from where it began to vibroorgan 2 with the maximum cell size and moved along the screen to the unloading side. When moving along the vibroorgan, grains of crushed stone with a size smaller than the cell size fell through on the bottom and were fed successively to the lower vibroorgans 3-5 with smaller cells. Before unloading, the coarse fraction was transported through the load-measuring sensor 9 installed on the bottom of the vibroorgan 2. Signals from the load-measuring sensor determining the mass of the fraction were recorded by the recording device 13. Similarly, the masses of other fractions were determined. The masses of the fractions were determined by comparing the average values of the signals, which are proportional to the contact pressure of the layer of material on the load sensors, measured at least three times,

Analysis of the mass transported by the vibroorgan material was carried out in the period corresponding to the phase angle of vibroorgan vibrations, i.e.

O11

% lp, tg + 2l: p oo

where ft) is the oscillation frequency;

t is the sowing time;

n - the number of vibroorgan vibrations after

turn it on.

To verify the method, the granulometric composition according to GOST 8269-76 was determined simultaneously. Fine crushed stone of the initial fraction 5-10 and 10-20 mm weighing 10 kg was loaded into the device bunker, which is greater than the minimum sample mass required by GOST 8269-76. The acceleration of vibrations of vibrating screens was 30 m / s2, the thickness of the rubble did not exceed 100 mm.

The results of the experiments are presented in the table.

From the table it follows that with the processing time (sieving) of the material within 60-90 s, the maximum error in determining the mass by the proposed method does not exceed 1%, which is considered acceptable (according to GOST 8269-76).

Claims (1)

Invention Formula The method for determining the granulometric composition of concrete aggregates, including transportation of a sample of the source material on movable arrays, characterized in that, in order to ensure continuous control of the composition of the aggregates of concrete and reduce the time for its implementation, the samples of the source material are movable on movable grids and the masses of the fractions are determined largest measured contact pressure of the layer of material acting on the sensitive elements of the smear-measuring devices during the joint izheni material layer with movable bars during one oscillation period in the range varying phase angle oscillations 9/6 PL-11/6 + x 2 n, where n - number vibroorgana oscillations.